U.S. patent number 7,728,933 [Application Number 11/289,447] was granted by the patent office on 2010-06-01 for method and apparatus of forming alignment layer for liquid crystal display device.
This patent grant is currently assigned to LG Display Co., Ltd.. Invention is credited to Chang Dong Kim, Hyun Sik Seo, Kwang Hoon Shin.
United States Patent |
7,728,933 |
Kim , et al. |
June 1, 2010 |
Method and apparatus of forming alignment layer for liquid crystal
display device
Abstract
A method for forming an alignment layer is disclosed, to prevent
light leakage generated by a physical contact between a rubbing
roll and a substrate, which includes preparing a substrate; coating
an alignment material on the substrate, for initial alignment of
liquid crystal; applying an electric field or a magnetic field to
the alignment material, for determination of alignment direction in
the alignment material; and curing the alignment material.
Inventors: |
Kim; Chang Dong (Seoul,
KR), Seo; Hyun Sik (Anyang-si, KR), Shin;
Kwang Hoon (Seoul, KR) |
Assignee: |
LG Display Co., Ltd. (Seoul,
KR)
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Family
ID: |
36779554 |
Appl.
No.: |
11/289,447 |
Filed: |
November 30, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060176432 A1 |
Aug 10, 2006 |
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Foreign Application Priority Data
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Feb 7, 2005 [KR] |
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10-2005-0011317 |
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Current U.S.
Class: |
349/124 |
Current CPC
Class: |
G02F
1/133723 (20130101); G02F 1/133765 (20210101); G02F
1/13378 (20130101) |
Current International
Class: |
G02F
1/1337 (20060101) |
Field of
Search: |
;349/124 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1178919 |
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Apr 1998 |
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CN |
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1 384 743 |
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Jul 2003 |
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EP |
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02-33127 |
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Feb 1990 |
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JP |
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04-372932 |
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Dec 1992 |
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JP |
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05-080340 |
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Apr 1993 |
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JP |
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06-118413 |
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Apr 1994 |
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JP |
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07-013168 |
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Jan 1995 |
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JP |
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09-197410 |
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Jul 1997 |
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JP |
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09-244024 |
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Sep 1997 |
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JP |
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09-244025 |
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Sep 1997 |
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JP |
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10-123525 |
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May 1998 |
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JP |
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11-133430 |
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May 1999 |
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JP |
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1998-026045 |
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Jul 1998 |
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KR |
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10-0210376 |
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Apr 1999 |
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KR |
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Primary Examiner: Dudek; James A
Attorney, Agent or Firm: McKenna Long & Aldridge LLP
Claims
What is claimed is:
1. A method for forming an alignment layer of an LCD device
comprising: preparing a substrate; coating an alignment material on
the substrate, for initial alignment of liquid crystal; applying a
field flux to the alignment material, for determination of
alignment direction of the alignment material; curing the alignment
material by using a heater at a temperature below 100.degree. C.,
wherein applying the field flux is performed with the field flux
application direction parallel to the X-axis, perpendicular to the
X-axis, or diagonal to the X-axis depending on the alignment
direction of the alignment material, and changing a direction of
the field flux by rotating a field flux generator while maintaining
the substrate stationary or by rotating the substrate while
maintaining the field flux generator stationary.
2. The method of claim 1, wherein the field flux is an electric
field.
3. The method of claim 2, wherein the electric field is applied in
the same direction as the alignment direction of the alignment
material when performing the step of applying the electric
field.
4. The method of claim 1, wherein the field flux is a magnetic
field.
5. The method of claim 4, wherein the magnetic field is applied
substantially perpendicular to the alignment direction of the
alignment material.
6. The method of claim 4, wherein applying the magnetic field is
performed with a pair of coiled electromagnets.
7. The method of claim 4, wherein applying the magnetic field is
performed with a horseshoe magnet.
8. he method of claim 1, wherein coating the alignment material,
applying the field flux, and curing the alignment material are
performed in sequence.
9. The method of claim 1, wherein the step of preparing the
substrate includes: defining a pixel region on a transparent
substrate by forming gate and data lines crossing each other;
forming a thin film transistor at an intersection of the gate and
data lines, the thin film transistor including a gate electrode, a
source electrode and a drain electrode; and forming a pixel
electrode connected with the drain electrode of the thin film
transistor.
10. The method of claim 1, wherein the step of preparing the
substrate includes: defining a pixel region on a transparent
substrate by forming gate and data lines crossing each other;
forming a thin film transistor at an intersection of the gate and
data lines, the thin film transistor including a gate electrode, a
source electrode and a drain electrode; forming a pixel electrode
connected with the drain electrode of the thin film transistor; and
forming a common electrode in parallel to the pixel electrode.
11. The method of claim 1, wherein the step of preparing the
substrate includes: forming a black matrix layer on a transparent
substrate, for prevention of light leakage; forming an R/G/B color
filter layer on the black matrix layer; and forming a common
electrode on the color filter layer.
12. The method of claim 1, wherein the step of preparing the
substrate includes: forming a black matrix layer on a transparent
substrate, for prevention of light leakage; forming an R/G/B color
filter layer on the black matrix layer; and forming an overcoat
layer on the color filter layer.
13. The method of claim 1, wherein the substrate is a plastic
substrate.
14. The method of claim 1, wherein the substrate is a flexible
substrate.
15. The method of claim 1, wherein the alignment material is formed
of a polymer selected from polyimide, polyamic acid,
polyvinylcinnamate, polyazobenzene, polyethyleneimine,
polyvinylalcohol, polyamide, polyethylene, polystylene,
polyphenylenephthalamide, polyester, polyurethane, or
polymethylmethacrylate.
16. The method of claim 1, wherein changing a field flux
application direction is performed by rotating a field flux
generator while maintaining the substrate stationary.
17. The method of claim 2, wherein the electric field is applied by
using an anode and a cathode coming into contact with both sides of
the substrate.
Description
This application claims the benefit of Korean Patent Application
No. P2005-0011317, filed on Feb. 7, 2005, which is hereby
incorporated by reference for all purposes as if fully set forth
herein.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display (LCD)
device, and more particularly, to an alignment layer for initial
alignment of liquid crystal in an LCD device.
2. Discussion of the Related Art
Among various ultra-thin flat type display devices, which include a
display screen having a thickness of several centimeters, a liquid
crystal display (LCD) device has great attention because of its
wide variety of uses, including notebook computers, monitors,
spacecraft, aircraft, and etc.
Generally, the LCD device includes a color filter substrate having
a color filter layer, a thin film transistor substrate having a
thin film transistor, and a liquid crystal layer formed between the
color filter substrate and the thin film transistor substrate. At
this time, the thin film transistor substrate is positioned
opposite to the color filter substrate.
In the LCD device, an alignment direction of the liquid crystal
layer is changed according to application of voltage, thereby
controlling the transmittance of light. Accordingly, images are
displayed in the LCD device. For application of voltage, electrodes
are formed on the thin film transistor substrate and the color
filter substrate. That is, a pixel electrode is formed on the thin
film transistor substrate, and a common electrode is formed on the
color filter substrate, whereby an electric field is vertically
formed between the thin film transistor substrate and the color
filter substrate (for example, Twisted Nematic (TN) mode). In
another method, the pixel electrode and the common electrode may be
formed on the thin film transistor substrate, thereby forming an
electric field parallel to the two substrates (for example,
In-Plane Switching (IPS) mode).
FIG. 1 is an exploded perspective view of a TN mode LCD device
according to the related art. As shown in FIG. 1, a thin film
transistor substrate 10 of the TN mode LCD device according to the
related art includes a gate line 12, a data line 14, a thin film
transistor T, and a pixel electrode 16. At this time, the thin film
transistor T is formed at a crossing of the gate and data lines 12
and 14, and the pixel electrode 16 is connected with the thin film
transistor T. Also, a color filter substrate 20 includes a black
matrix layer 22 including black matrix patterns for prevention of
light leakage, a R/G/B color filter layer 24 having red, green and
blue color patterns, each color pattern provided between the black
matrix patterns, and a common electrode 25 formed on the R/G/B
color filter layer 24. In this case, an electric field is
vertically formed between the pixel electrode 16 of the thin film
transistor substrate 10 and the common electrode 25 of the color
filter substrate 20, thereby controlling the alignment direction of
liquid crystal.
Thereafter, the substrates 10 and 20 are attached to each other to
form one liquid crystal panel in which a liquid crystal layer is
formed between the substrates 10 and 20.
In the meantime, when forming the liquid crystal layer between the
two substrates 10 and 20, regular alignment of liquid crystal
molecules is required. For this, although not shown, alignment
layers are provided on the thin film transistor substrate 10 and
the color filter substrate 20 for initial alignment of liquid
crystal.
The alignment layer for initial alignment of liquid crystal is
generally formed in a rubbing alignment method.
The rubbing alignment method includes steps of coating a thin
filming of an organic polymer such as polyimide on a substrate,
aligning a side chain of the organic polymer to a predetermined
direction by rubbing the coated organic polymer by rotating a
rubbing roll coated with rubbing cloth, and curing the aligned
organic polymer.
Accordingly, the liquid crystal is aligned according to the aligned
direction of the side chain of the organic polymer. That is, the
moving direction of the rubbing roll corresponds to the alignment
direction of liquid crystal.
However, the rubbing alignment method has the following
disadvantages.
First, when the rubbing cloth is irregular, there may be resulting
light leakage because of improper or no alignment of the liquid
crystal.
FIG. 2 is a perspective view of illustrating the problem generated
by the irregular rubbing cloth.
As illustrated in FIG. 2, the elements such as the thin film
transistor, the color filter layer and the electrode layer are
formed on the substrate. Thus, when the rubbing roll 30 coated with
the rubbing cloth 32 rotates on the elements formed on the
substrate 10 or 20, some portion 32a of the rubbing cloth 32 may be
irregular. As a result, the side chain of the organic polymer on
the portion of the substrate rubbed with the irregular portion 32a
of the rubbing cloth 32 is not aligned or not aligned properly.
Therefore, there may be the light leakage due to the irregular
alignment of liquid crystal.
Second, when the rubbing cloth does not in contact with the
substrate, there may be light leakage.
FIG. 3 is a perspective view illustrating the alignment state of
liquid crystal when the rubbing cloth is not in contact with the
substrate.
As explained earlier, electrode layers, such as pixel electrodes
and a common electrode, are formed on a substrate. Due to a step
height in electrode layers formed on a substrate 10, as illustrated
in FIG. 3, a region (region "A") is formed where a rubbing cloth 32
does not come into contact with the substrate 10. In this case, the
alignment of a liquid crystal is not uniform in the region ("A"),
resulting in light leakage.
In conclusion, according to a related art rubbing alignment method,
when the arrangement of a rubbing cloth is non-uniform or a rubbing
cloth does not come into contact with a substrate, rubbing cannot
be performed well, causing the problem of light leakage. Thus,
there is a need for a novel liquid crystal alignment method to
solve the problems of the related art rubbing alignment method.
The above-mentioned problems of the related art rubbing alignment
method are attributed to physical contact between a rubbing roll
and a substrate.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a method for
forming an alignment layer that substantially obviates one or more
problems due to limitations and disadvantages of the related
art.
An advantage of the present invention is to provide a method for
forming an alignment layer to prevent light leakage caused by
physical contact between a rubbing roll and a substrate.
Another advantage of the present invention is to provide an
alignment layer formation unit to prevent light leakage caused by
physical contact between a rubbing roll and a substrate.
Additional features and advantages of the invention will be set
forth in part in the description which follows and in part will
become apparent to those having ordinary skill in the art upon
examination of the following or may be learned from practice of the
invention. The objectives and other advantages of the invention may
be realized and attained by the structure particularly pointed out
in the written description and claims hereof as well as the
appended drawings.
To achieve these and other advantages and in accordance with the
purpose of the invention, as embodied and broadly described herein,
a method for forming an alignment layer of an LCD device includes
steps of preparing a substrate; coating an alignment material on
the substrate, for initial alignment of liquid crystal; applying an
electric field or a magnetic field to the alignment material, for
determination of alignment direction in the alignment material; and
curing the alignment material.
Instead of a related rubbing alignment method, a method for forming
an alignment layer according to the present invention uses a field
flux (e.g., an electric field or magnetic field) application method
which does not require physical contact for a substrate.
At this time, the alignment direction of the alignment material is
identical to the electric field application direction, and is
perpendicular to the magnetic field application direction.
Accordingly, it is preferable to apply the electric field in the
same direction as the alignment direction of the alignment
material. Also, it is preferable to apply the magnetic field in
perpendicular to the alignment direction of the alignment
material.
The electric field application method may use an electromagnet or a
horseshoe magnet.
The step of applying an electric or magnetic field can be carried
out by varying the direction of the field applied in a direction
parallel, perpendicular or diagonal to the X-axis depending on the
alignment direction of the alignment material. At this time,
variation in the direction of the electric or magnetic field
applied can be performed by rotating an electric or magnetic field
generator while fixing the substrate applied with the alignment
material, or rotating the substrate applied with the alignment
material while fixing an electric or magnetic field generator.
The steps of coating the alignment material, applying the electric
or magnetic field, and curing the alignment material are performed
in sequence, for the decrease of process time.
In another aspect of the present invention, an alignment layer
formation unit includes a substrate stage on which a substrate is
loaded; an electric or magnetic field application part, formed in
the periphery of the substrate stage; and a curing part for curing
an alignment material of the substrate.
The electric field generator may include an anode and a cathode
opposite to the anode through the substrate stage.
The magnetic field generator may be formed in such a manner that a
horseshoe magnet surrounds the substrate stage or a pair of coiled
electromagnets face each other through the substrate stage.
In addition, an alignment layer applicator may be provided before
the electric field generator or the magnetic field generator.
In this case, the substrate stage may be moveable so as to
consecutively move the substrate to the alignment layer applicator
and the electric or magnetic field generator.
The electric or magnetic field generator may be rotatable so that
the direction of the electric or magnetic field applied can be
properly varied depending on the alignment direction of the
alignment material.
It is to be understood that both the foregoing general description
and the following detailed description of the present invention are
exemplary and explanatory and are intended to provide further
explanation of the invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
FIG. 1 is an exploded perspective view of illustrating an LCD
device according to the related art;
FIGS. 2 and 3 are perspective views of illustrating problems of
rubbing alignment according to the related art;
FIGS. 4A to 4D are process diagrams illustrating forming an
alignment layer of an LCD device according to embodiment of the
present invention;
FIGS. 5A to 5C are process diagrams of showing the process for
applying an electric field in an LCD device according to another
embodiment of the present invention;
FIGS. 6A to 6D are process diagrams illustrating forming an
alignment layer of an LCD device according to another embodiment of
the present invention;
FIG. 7 illustrates an alignment layer formation unit according to
an embodiment of the present invention;
FIG. 8 illustrates an alignment layer formation unit according to
another embodiment of the present invention; and
FIG. 9 illustrates an alignment layer formation unit according to
another embodiment of the present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Reference will now be made in detail to embodiments of the present
invention, examples of which are illustrated in the accompanying
drawings. Wherever possible, the same reference numbers will be
used throughout the drawings to refer to the same or like
parts.
Hereinafter, a method for forming an alignment layer according to
the present invention will be described with reference to the
accompanying drawings. As illustrated in the embodiments described
herein, according to the present invention, a field flux (e.g., an
electric field or a magnetic field) may be applied to an alignment
layer to provide an alignment direction in accordance with the
direction of the field flux.
FIGS. 4A to 4D illustrate forming an alignment layer of an LCD
device by application of an electric field according to one
embodiment of the present invention.
First, as illustrated in FIG. 4A, a substrate 100 is prepared. The
substrate 100 is one substrate for an LCD device, which may be a
thin film transistor substrate including a thin film transistor, or
may be a color filter substrate including a color filter layer. In
this case, when the substrate is formed of the thin film transistor
substrate or the color filter substrate, elements formed on the
substrate may vary depending on the mode of the LCD device.
For example, in the case where the substrate 100 is a thin film
transistor substrate for a TN (twisted nematic) mode liquid crystal
display, gate lines and data lines crossing each other on a
transparent substrate are formed to define pixel regions; thin film
transistors including a gate electrode, a source electrode and a
drain electrode are formed at crossings of the gate lines and the
data lines; and pixel electrodes are formed within the pixel
regions to connect to the drain electrode of the thin film
transistors.
Further, in the case where the substrate 100 is a thin film
transistor substrate for an in-plane switching (IPS) mode liquid
crystal display, gate lines and data lines crossing each other on a
transparent substrate are formed to define pixel regions; thin film
transistors including a gate electrode, a source electrode and a
drain electrode are formed at crossings of the gate lines and the
data lines; pixel electrodes are formed within the pixel regions to
connect to the drain electrode of the thin film transistors; and a
common electrode is formed substantially parallel to the pixel
electrodes.
Further, in the case where the substrate 100 is a color filter
substrate for a TN mode liquid crystal display, a light-blocking
layer is formed on a transparent substrate to prevent light from
leaking; a green/red/blue color filter layer is formed on the
light-blocking layer; and a common electrode is formed on top of
the color filter layer.
Further, in the case where the substrate 100 is a color filter
substrate for an IPS mode liquid crystal display, a light-blocking
layer is formed on a transparent substrate to prevent light from
leaking; a green/red/blue color filter layer is formed on the
light-blocking layer; and an overcoat layer is formed on top of the
color filter layer to planarize the substrate.
Modifications and variations of the materials and formation methods
of the constituent elements formed on the substrate 100 will be
appreciated by those skilled in the art.
In addition to a glass substrate, a flexible substrate or a plastic
substrate can also be used as the transparent substrate.
Since physical contact occurs between a rubbing roll and a
substrate in related art rubbing alignment methods, the use of
flexible substrates causes problems. In contrast, since the method
of the present invention uses a field flux (e.g., an electric field
or a magnetic field), no physical contact is caused, which will be
described in detail below. Accordingly, there is no problem in
using flexible substrates in the present invention.
In the related art rubbing alignment method, it is necessary to
coat an alignment material and to cure the coated alignment
material. In the related art, the coated alignment material is
cured at a high temperature of about 230.degree. C. Accordingly, if
a plastic substrate is used in the related art rubbing alignment
method, the plastic substrate may be damaged or bent since plastic
is very weak in heat.
However, in case of the alignment method according to the present
invention which uses the electric field, a curing process is
performed at a temperature below 100.degree. C. Thus, the plastic
substrate which is weak in relatively high heat in related art
curing may be used in the alignment method according to the present
invention.
Referring to FIG. 4B, an alignment material 200 is coated on the
substrate. The alignment material 200 may be formed any material of
which an alignment direction is determined with application of
electric field. The alignment material 200 may be formed of polymer
selected from polyimide, polyamic acid, polyvinylcinnamate,
polyazobenzene, polyethyleneimine, polyvinylalcohol, polyamide,
polyethylene, polystylene, polyphenylenephthalamide, polyester,
polyurethane, or polymethylmethacrylate.
Then, as illustrated in FIG. 4C, an electric field E is applied to
the alignment material 200 using an electric field generator 300 to
determine the alignment direction of the alignment material
200.
The electric field generator 300 includes an anode 310 and a
cathode 320 opposite to the anode through the substrate 100 applied
with the alignment material 200. The electric field E is applied
from the anode 310 to the cathode 320 as indicated by an arrow.
Although the anode 310 and the cathode 320 do not come into contact
with the substrate 100 in the figure, it is preferred that the
anode 310 and the cathode 320 come into contact with both sides of
the substrate 100 in view of the intensity of the electric field
applied.
The alignment material 200 is aligned in the direction of electric
field. The electric field may be applied in the same direction as
the alignment direction of the alignment material 200.
Accordingly, where it is desired to align the alignment material
200 in the direction parallel to the x axis, an electric field may
be applied in the direction parallel to the x axis, as illustrated
in FIG. 5A. Where it is desired to align the alignment material 200
in the direction perpendicular to the x axis, an electric field may
be applied in the direction perpendicular to the x axis, as
illustrated in FIG. 5B. Where it is desired to align the alignment
material 200 in the direction diagonal to the x axis, an electric
field may be applied in the direction diagonal to the x axis, as
illustrated in FIG. 5C.
To vary the direction of the electric field applied, as illustrated
in FIGS. 5A to 5C, the electric field generator 300 or the
substrate 100 may be rotated.
Referring to FIG. 4D, the curing process is performed. After
determining the alignment direction of the alignment material 200
by application of the electric field, the alignment material 200 is
cured, whereby the alignment direction of the alignment material
200 is fixed.
The curing process is performed by applying heat, wherein a
temperature for the curing process may be varied according to the
kind of the substrate applied. As mentioned above, if using the
plastic substrate, the curing process may be performed at a
temperature below about 100.degree. C.
Coating the alignment material 200 (shown in FIG. 4B), applying the
electric field (shown in FIG. 4C), performing the curing process
(shown in FIG. 4D), may be performed consecutively thereby
decreasing the process time.
FIGS. 6A to 6D are process diagrams schematically illustrating
forming an alignment layer for a liquid crystal display by
application of a magnetic field according to another embodiment of
the present invention.
First, as illustrated in FIG. 6A, a substrate 100 is prepared.
Constituent elements that can be formed on the substrate 100 may
vary depending on the mode of liquid crystal displays, as in the
previous embodiment. In addition to a glass substrate, a
transparent substrate, such as a flexible substrate or a plastic
substrate, can be used in the present invention.
Then, as illustrated in FIG. 6B, an alignment material 200 is
applied to the substrate.
The kinds of the alignment material 200 are the same as those
described in the previous embodiment.
Then, as illustrated in FIG. 6C, a magnetic field B is applied to
the alignment material 200 using a magnetic field generator 400 or
500 to determine the alignment direction of the alignment material
200.
The magnetic field B can be applied using an electromagnet system
in which a pair of electromagnets 400 wound with coils 420 are
arranged to face each other through the substrate, as illustrated
in FIG. 6C(1), or a horseshoe magnet surrounding the substrate as
illustrated in FIG. 6C(2), but the present invention is not limited
thereto.
In case of the previous embodiment of the present invention, the
electrodes of the electric field generator may be connected to the
substrate when applying the electric field. Such process requires
an additional step for connecting the electrode part to the
substrate. In case of the present embodiment of the present
invention, it is unnecessary to provide an additional process for
connecting an magnetic field application part to the substrate.
Thus, the process of applying the magnetic field may provide a
greater yield than the process of applying the electric field.
Since the alignment material 200 is aligned in the direction
perpendicular to the direction of the magnetic field applied, the
magnetic field may be applied in the direction perpendicular to the
alignment direction of the alignment material 200.
To vary the direction of the magnetic field applied, the magnetic
field generator 400 or 500 or the substrate 100 may be rotated.
After that, as shown in FIG. 6D, a curing process is performed.
The curing process is performed by applying heat, wherein a
temperature for the curing process may be varied according to the
type of the substrate used. As mentioned above, if using a plastic
or flexible substrate, the curing process may be performed at a
temperature below about 100.degree. C.
Coating the alignment material 200 (shown in FIG. 6B), applying the
magnetic field (shown in FIG. 6C), and performing the curing
process (shown in FIG. 6D) may be performed consecutively thereby
decreasing the process time.
FIG. 7 schematically illustrates an apparatus for forming an
alignment layer for a liquid crystal display by application of an
electric field according to one embodiment of the present
invention.
The alignment layer formation unit is provided with a substrate
stage 600, an electric field generator 300, and a curing part 800.
At this time, a substrate is put on the substrate stage 600, and
the electric field generator 300 is formed at the periphery of the
substrate stage 600. Also, the curing part 800 is provided to cure
an alignment material.
The electric field generator 300 includes an anode 310 and a
cathode 320 opposite to the anode through the substrate stage 600.
An electric field is applied to a substrate 100 securely mounted on
the substrate stage 600. Before the application of the electric
field, an alignment material 200 is applied to the substrate
100.
The electric field 300 may be rotated according to the alignment
direction of the alignment material 200.
The curing part 800 may include a heater which emits heat to the
alignment material 200.
Also, an alignment layer applicator 700 may be arranged before the
electric field generator 300. The alignment layer coating part 700
may be a printing system but it is not limited to this.
In this case, the substrate stage 600 having the substrate 100 is
consecutively moved through the alignment layer applicator 700, the
electric field generator 300, and the curing part 800.
FIGS. 8 and 9 schematically illustrate apparatuses for forming an
alignment layer for a liquid crystal display by application of a
magnetic field according to another embodiment of the present
invention.
The alignment layer formation unit is provided with a substrate
stage 600, magnetic field generators 400 and 500, and a curing part
800. At this time, a substrate is put on the substrate stage 600,
and the magnetic field generators 400 and 500 are provided at the
periphery of the substrate stage 600. Also, the curing part 800 is
provided to cure an alignment material.
The magnetic field generator may be an electromagnet system 500 in
which a pair of electromagnets 400 wound with coils 420 are
arranged to face each other through the substrate as illustrated in
FIG. 8, or a horseshoe magnet 500 surrounding the substrate as
illustrated in FIG. 9, but the present invention is not limited to
these structures. Any apparatus can be used so long as it can
generate a magnetic field.
The magnetic field generator 400 or 500 may be rotatable so that
the direction of the magnetic field applied can be properly varied
depending on the alignment direction of the alignment material.
The curing part 800 may include a heater which emits heat to the
alignment material 200.
Also, an alignment layer application 700 may be arranged before the
magnetic field generators 400 and 500. The alignment layer
applicator 700 may be a printing system, but it is not limited to
this.
In this case, the substrate stage 600 having the substrate 100 may
be consecutively moved through the alignment layer applicator 700,
the magnetic field generators 400 and 500, and the curing part
800.
As mentioned above, the method for forming the alignment layer and
the alignment layer formation unit according to the related art
have the following advantages.
As apparent from the above description, according to the present
invention, since the alignment direction of an alignment material
is determined by using a field flux (e.g., an electric or magnetic
field), no physical contact with a substrate is required and thus
the problem of light leakage caused by rubbing alignment can be
solved.
Also, the curing process for the alignment material may be
performed at a temperature below about 100.degree. C. Thus, it is
possible to use a plastic substrate which is weak in heat, or to
use a flexible substrate.
In addition, it is possible to consecutively perform the steps of
coating the alignment material, applying the electric field or the
magnetic field, and curing the alignment material, thereby
decreasing the process time.
By rotation of the electric or magnetic field application part, it
is possible to change the alignment direction of the alignment
material.
It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *